BOOTPTAB

NAME

bootptab - Internet Bootstrap Protocol server database

DESCRIPTION

The
bootptab
file is the configuration database file for
bootpd,
the Internet Bootstrap Protocol server.
It's format is similar to that of
termcap(5)
in which two-character case-sensitive tag symbols are used to
represent host parameters. These parameter declarations are separated by
colons (:), with a general format of:

hostname:tg=value... :tg=value... :tg=value. ...

wherehostname
is the actual name of a bootp client (or a "dummy entry"), and
tg
is a two-character tag symbol. Dummy entries have an invalid hostname
(one with a "." as the first character) and are used to provide
default values used by other entries via the
tc=.dummy-entry
mechanism. Most tags must be followed by an equals-sign
and a value as above. Some may also appear in a boolean form with no
value (i.e.
:tg:).
The currently recognized tags are:

bfBootfile

bsBootfile size in 512-octet blocks

csCookie server address list

dfMerit dump file

dlDHCP lease time in seconds

dnDomain name

dsDomain name server address list

efExtension file

exYork ex option (huh?)

gwGateway address list

haHost hardware address

hdBootfile home directory

hnSend client's hostname to client

htHost hardware type (see Assigned Numbers RFC)

imImpress server address list

ipHost IP address

lgLog server address list

lpLPR server address list

msMessage size

nsIEN-116 name server address list

ntNTP (time) Server (RFC 1129)

raReply address override

rlResource location protocol server address list

rpRoot path to mount as root

saTFTP server address client should use

smHost subnet mask

swSwap server address

tcTable continuation (points to similar "template" host entry)

tdTFTP root directory used by "secure" TFTP servers

toTime offset in seconds from UTC

tsTime server address list

vmVendor magic cookie selector

ydYP (NIS) domain name

ysYP (NIS) server address

There is also a generic tag,
Tn,
where
n
is an RFC1084 vendor field tag number. Thus it is possible to immediately
take advantage of future extensions to RFC1084 without being forced to modify
bootpd
first. Generic data may be represented as either a stream of hexadecimal
numbers or as a quoted string of ASCII characters. The length of the generic
data is automatically determined and inserted into the proper field(s) of the
RFC1084-style bootp reply.

The following tags take a whitespace-separated list of IP addresses:
cs,
ds,
gw,
im,
lg,
lp,
ns,
nt,
ra,
rl,
and
ts.
The
ip,
sa,
sw,
sm,
and
ys
tags each take a single IP address.
All IP addresses are specified in standard Internet "dot" notation
and may use decimal, octal, or hexadecimal numbers
(octal numbers begin with 0, hexadecimal numbers begin with '0x' or '0X').
Any IP addresses may alternatively be specified as a hostname, causing
bootpd
to lookup the IP address for that host name using
gethostbyname(3).
If the
ip
tag is not specified,
bootpd
will determine the IP address using the entry name as the host name.
(Dummy entries use an invalid host name to avoid automatic IP lookup.)

The
ht
tag specifies the hardware type code as either an unsigned decimal, octal, or
hexadecimal integer or one of the following symbolic names:
ethernet
or
ether
for 10Mb Ethernet,
ethernet3
or
ether3
for 3Mb experimental Ethernet,
ieee802,
tr,
or
token-ring
for IEEE 802 networks,
pronet
for Proteon ProNET Token Ring, or
chaos,
arcnet,
or
ax.25
for Chaos, ARCNET, and AX.25 Amateur Radio networks, respectively.
The
ha
tag takes a hardware address which may be specified as a host name
or in numeric form. Note that the numeric form
must
be specified in hexadecimal; optional periods and/or a leading '0x' may be
included for readability. The
ha
tag must be preceded by the
ht
tag (either explicitly or implicitly; see
tc
below).
If the hardware address is not specified and the type is specified
as either "ethernet" or "ieee802", then
bootpd
will try to determine the hardware address using
ether_hton(3).

The hostname, home directory, and bootfile are ASCII strings which may be
optionally surrounded by double quotes ("). The client's request and the
values of the
hd
and
bf
symbols determine how the server fills in the bootfile field of the bootp
reply packet.

If the client provides a file name it is left as is.
Otherwise, if the
bf
option is specified its value is copied into the reply packet.
If the
hd
option is specified as well, its value is prepended to the
boot file copied into the reply packet.
The existence of the boot file is checked only if the
bs=auto
option is used (to determine the boot file size).
A reply may be sent whether or not the boot file exists.

Some newer versions of
tftpd(8)
provide a security feature to change their root directory using
the
chroot(2)
system call.
The
td
tag may be used to inform
bootpd
of this special root directory used by
tftpd.
(One may alternatively use the
bootpd-cchdir
option.)
The
hd
tag is actually relative to the root directory specified by the
td
tag.
For example, if the real absolute path to your BOOTP client bootfile is
/tftpboot/bootfiles/bootimage,
and
tftpd
uses
/tftpboot
as its "secure" directory, then specify the following in
bootptab:

:td=/tftpboot:hd=/bootfiles:bf=bootimage:

If your bootfiles are located directly in /tftpboot, use:

:td=/tftpboot:hd=/:bf=bootimage:

The
sa
tag may be used to specify the IP address of the particular TFTP server
you wish the client to use. In the absence of this tag,
bootpd
will tell the client to perform TFTP to the same machine
bootpd
is running on.

The time offset
to
may be either a signed decimal integer specifying the client's
time zone offset in seconds from UTC, or the keyword
auto
which uses the server's time zone offset. Specifying the
to
symbol as a boolean has the same effect as specifying
auto
as its value.

The bootfile size
bs
may be either a decimal, octal, or hexadecimal integer specifying the size of
the bootfile in 512-octet blocks, or the keyword
auto
which causes the server to automatically calculate the bootfile size at each
request. As with the time offset, specifying the
bs
symbol as a boolean has the same effect as specifying
auto
as its value.

The vendor magic cookie selector (the
vm
tag) may take one of the following keywords:
auto
(indicating that vendor information is determined by the client's request),
rfc1048
or
rfc1084
(which always forces an RFC1084-style reply), or
cmu
(which always forces a CMU-style reply).

The
hn
tag is strictly a boolean tag; it does not take the usual equals-sign and
value. It's presence indicates that the hostname should be sent to RFC1084
clients.
Bootpd
attempts to send the entire hostname (including domain) as it is specified in the configuration
file; if this will not fit into the reply packet, the name is shortened to
just the host field (up to the first period, if present) and then tried.
In no case is an arbitrarily-truncated hostname sent (if nothing reasonable
will fit, nothing is sent).

Often, many host entries share common values for certain tags (such as name
servers, etc.). Rather than repeatedly specifying these tags, a full
specification can be listed for one host entry and shared by others via the
tc
(table continuation) mechanism.
Often, the template entry is a dummy host which doesn't actually exist and
never sends bootp requests. This feature is similar to the
tc
feature of
termcap(5)
for similar terminals. Note that
bootpd
allows the
tc
tag symbol to appear anywhere in the host entry, unlike
termcap
which requires it to be the last tag. Information explicitly specified for a
host always overrides information implied by a
tc
tag symbol, regardless of its location within the entry. The
value of the
tc
tag may be the hostname or IP address of any host entry
previously listed in the configuration file.

Sometimes it is necessary to delete a specific tag after it has been inferred
via
tc.
This can be done using the construction
tag@
which removes the effect of
tag
as in
termcap(5).
For example, to completely undo an IEN-116 name server specification, use
":ns@:" at an appropriate place in the configuration entry. After removal
with
@,
a tag is eligible to be set again through the
tc
mechanism.

Blank lines and lines beginning with "#" are ignored in the configuration
file. Host entries are separated from one another by newlines; a single host
entry may be extended over multiple lines if the lines end with a backslash
(\). It is also acceptable for lines to be longer than 80 characters. Tags
may appear in any order, with the following exceptions: the hostname must be
the very first field in an entry, and the hardware type must precede the
hardware address.